perf tools: Add cpu_topology object

Make struct cpu_topo global and rename it to 'struct cpu_topology', so
that it can be used from the 'perf record' command in the following
patches.

Add the following interface functions to load/free cpu topology details:

  struct cpu_topology *cpu_topology__new(void);
  void cpu_topology__delete(struct cpu_topology *tp);

Move it to a separate source file cputopo.c together with numa related
object in the following patches.

No functional change, the new interface will be used in upcoming changes.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20190219095815.15931-3-jolsa@kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>